24ACB7
Performancet Series Air Conditioner
with Puronr Refrigerant
2 To 5 Nominal Tons
Installation Instructions
SAFETY CONSIDERATIONS
INSTALLATION RECOMMENDATIONS
NOTE: Read the entire instruction manual before starting the
installation.
Improper installation, adjustment, alteration, service, maintenance,
or use can cause explosion, fire, electrical shock, or other
conditions which may cause death, personal injury, or property
damage. Consult a qualified installer, service agency, or your
distributor or branch for information or assistance. The qualified
installer or agency must use factory−authorized kits or accessories
when modifying this product. Refer to the individual instructions
packaged with the kits or accessories when installing.
Follow all safety codes. Wear safety glasses, protective clothing,
and work gloves. Use quenching cloth for brazing operations.
Have fire extinguisher available. Read these instructions
thoroughly and follow all warnings or cautions included in
literature and attached to the unit. Consult local building codes and
current editions of the National Electrical Code (NEC) NFPA 70.
In Canada, refer to current editions of the Canadian electrical code
CSA 22.1.
NOTE: In some cases noise in the living area has been traced to
gas pulsations from improper installation of equipment.
1. Locate unit away from windows, patios, decks, etc. where
unit operation sound may disturb customer.
2. Ensure that vapor and liquid tube diameters are appropriate
for unit capacity.
3. Run refrigerant tubes as directly as possible by avoiding unnecessary turns and bends.
4. Leave some slack between structure and unit to absorb vibration.
5. When passing refrigerant tubes through the wall, seal opening with RTV or other pliable silicon−based caulk. (See Fig.
1.)
6. Avoid direct tubing contact with water pipes, duct work,
floor joists, wall studs, floors, and walls.
7. Do not suspend refrigerant tubing from joists and studs with
a rigid wire or strap which comes in direct contact with
tubing.(See Fig. 1.)
8. Ensure that tubing insulation is pliable and completely surrounds vapor tube.
9. When necessary, use hanger straps which are 1 in. (25.4
mm) wide and conform to shape of tubing insulation. (See
Fig. 1.)
10. Isolate hanger straps from insulation by using metal sleeves
bent to conform to shape of insulation.
Recognize safety information. This is the safety−alert symbol
When you see this symbol on the unit and in instructions or
manuals, be alert to the potential for personal injury. Understand
these signal words; DANGER, WARNING, and CAUTION. These
words are used with the safety−alert symbol. DANGER identifies
the most serious hazards which will result in severe personal injury
or death. WARNING signifies hazards which could result in
personal injury or death. CAUTION is used to identify unsafe
practices which would result in minor personal injury or product
and property damage. NOTE is used to highlight suggestions
which will result in enhanced installation, reliability, or operation.
NOTE: Avoid contact between tubing and structure
OUTDOOR WALL
WARNING
!
INDOOR WALL
CAULK
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury or death.
Before installing, modifying, or servicing system, main
electrical disconnect switch must be in the OFF position.
There may be more than 1 disconnect switch. Lock out and
tag switch with a suitable warning label.
!
WARNING
EXPLOSION HAZARD
Failure to follow this warning could
result in death, serious personal injury,
and/or property damage.
Never use air or gases containing
oxygen for leak testing or operating
refrigerant compressors. Pressurized
mixtures of air or gases containing
oxygen can lead to an explosion.
LIQUID TUBE
VAPOR TUBE
INSULATION
THROUGH THE WALL
JOIST
HANGER STRAP
(AROUND VAPOR
TUBE ONLY)
INSULATION
VAPOR TUBE
1” (25.4 mm) MIN.
LIQUID TUBE
SUSPENSION
A94026
Fig. 1 − Piping Installation
The outdoor unit contains system refrigerant charge for operation
with AHRI rated indoor unit when connected by 15 ft. (4.57 m) of
field−supplied or factory accessory tubing. For proper unit
operation, check refrigerant charge using charging information
located on control box cover and/or in the Check Charge section of
this instruction.
IMPORTANT: Maximum liquid−line size is 3/8−in. OD for all
residential applications including long line.
IMPORTANT: Always install the factory−supplied liquid−line
filter drier. If replacing the filter drier, refer to Product Data Digest
for appropriate part number. Obtain replacement filter driers from
your distributor or branch.
INSTALLATION
operating voltage is 230v. For 208v applications, the maximum
outdoor ambient is 120_F (48.9 _C).
NOTE: Units operating at high stage operation, 208v (or below)
line voltage and at an outdoor ambient of 120_F (or greater), may
experience compressor trip.
Make Piping Connections
!
PERSONAL INJURY AND ENVIRONMENTAL
HAZARD
CAUTION
Failure to follow this warning could result in personal injury
or death.
Relieve pressure and recover all refrigerant before system
repair or final unit disposal. Use all service ports and open
all flow−control devices, including solenoid valves.
CUT HAZARD
Failure to follow this caution may result in personal injury.
24ACB7
WARNING
!
IMPORTANT: Effective January 1, 2015, all split system and
packaged air conditioners must be installed pursuant to applicable
regional efficiency standards issued by the Department of Energy.
Sheet metal parts may have sharp edges or burrs. Use care and
wear appropriate protective clothing and gloves when
handling parts.
Federal regulations require that you do not vent refrigerant
to the atmosphere. Recover during system repair or final
unit disposal.
Check Equipment and Job Site
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage or improper operation.
Inspect Equipment
File claim with shipping company prior to installation if shipment
is damaged or incomplete. Locate unit rating plate on unit corner
panel. It contains information needed to properly install unit.
Check rating plate to be sure unit matches job specifications.
If ANY refrigerant tubing is buried, provide a 6−in (152.4
mm) vertical rise at service valve. Refrigerant tubing lengths
up to 36−in (914.4 mm) may be buried without further
special consideration. Do not bury lines more than 36−in.
(914.4 mm).
Install on a Solid, Level Mounting Pad
If conditions or local codes require the unit be attached to pad, tie
down bolts should be used and fastened through knockouts
provided in unit base pan. Refer to unit mounting pattern in Fig. 2
to determine base pan size and knockout hole location.
For hurricane tie downs, contact local distributor for details and PE
(Professional Engineer) certification, if required by local
authorities.
On rooftop applications, mount on level platform or frame. Place
unit above a load−bearing wall and isolate unit and tubing set from
structure. Arrange supporting members to adequately support unit
and minimize transmission of vibration to building. Consult local
codes governing rooftop applications.
Roof mounted units exposed to winds may require wind baffles.
Consult the Application Guideline and Service Manual −
Residential Split System Air Conditioners and Heat Pumps for
wind baffle construction.
NOTE: Unit must be level to within ±2_ (±3/8 in./ft,±9.5 mm/m.)
per compressor manufacturer specifications.
Clearance Requirements
When installing, allow sufficient space for airflow clearance,
wiring, refrigerant piping, and service. Allow 24 in. (609.6 mm)
clearance to service end of unit and 48 in. (1219.2 mm) (above
unit. For proper airflow, a 6−in. (152.4 mm) clearance on 1 side of
unit and 12−in. (304.8 mm) on all remaining sides must be
maintained. Maintain a distance of 24 in. (609.6 mm) between
units. Position so water, snow, or ice from roof or eaves cannot fall
directly on unit.
On rooftop applications, locate unit at least 6 in. (152.4 mm) above
roof surface.
Operating Ambient
The minimum outdoor operating ambient in cooling mode is 55_F
(12.78_C) without accessories and as low as 0_F (−17.78_C) with
approved low−ambient accessory kits, and the maximum outdoor
operating ambient in cooling mode is 125_F (51.67_C) when
CAUTION
!
UNPACK UNIT
Move to final location. Remove carton taking care not to damage
unit.
3/8-in. (9.53 mm) Dia.
Tiedown Knockouts in
Basepan(2) Places
View From Top
UNIT BASE PAN
Dimension in. (mm)
31–1/2 X 31–1/2
(800 X 800)
35 X 35
(889 X 889)
TIEDOWN KNOCKOUT LOCATIONS in. (mm)
A
B
C
9–1/8 (231.8)
6–9/16 (166.7)
24–11/16 (627.1)
9–1/8 (231.8)
6–9/16 (166.7)
28–7/16 (722.3)
A05177
Fig. 2 − Tiedown Knockout Locations
Outdoor units may be connected to indoor section using accessory
tubing package or field−supplied refrigerant grade tubing of correct
size and condition. Rated tubing diameters shown in Table 1 are
recommended up to 80 ft. (24.38 m). See Product Data for
acceptable alternate vapor diameters and associated capacity losses.
For tubing requirements beyond 80 ft. (24.38 m), substantial
capacity and performance losses can occur. Following the
recommendations in the Longline Guideline will reduce these
losses. Refer to Table 1 for field tubing diameters. Refer to Table 2
for accessory requirements.
There are no buried−line applications greater than 36−in. (914.4
mm) allowed.
If refrigerant tubes or indoor coil are exposed to atmosphere, they
must be evacuated to 500 microns to eliminate contamination and
moisture in the system.
2
Outdoor Unit Connected to Factory Approved Indoor
Unit
Outdoor unit contains correct system refrigerant charge for
operation with factory approved ARI rated indoor unit when
connected by 15 ft. (4.57 m) of field−supplied or factory−accessory
tubing, and factory supplied filter drier. Check refrigerant charge
for maximum efficiency.
Refrigerant Tubing Connection Outdoor
Sweat Connection
!
A05178
Fig. 3 − Liquid Line Filter Drier
Evacuate Refrigerant Tubing and Indoor Coil
CAUTION
CAUTION
!
UNIT DAMAGE HAZARD
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage or improper operation.
Failure to follow this caution may result in equipment
damage or improper operation.
Service valves must be wrapped in a heat−sinking material
such as a wet cloth while brazing.
Never use the system compressor as a vacuum pump.
Table 1 – Refrigerant Connections and Recommended Liquid
and Vapor Tube Diameters (In.)
LIQUID
RATED VAPOR*
Connection
Connection
Tube
& Max. Tube
Diameter
Diameter
Diameter
24
3/8
3/4
3/4
36
3/8
7/8
7/8
48
3/8
7/8
1-1/8
60
3/8
7/8
1-1/8
* Units are rated with 25 ft. (7.6 m) of lineset. See Product Data sheet for
performance data when using different size and length linesets.
Notes:
1. Do not apply capillary tube or fixed orifice indoor coils to these units.
2. For Tubing Set lengths between 80 and 200 ft. (24.38 and 60.96 m)
horizontal or 35 ft. (10.7 m) vertical differential 250 ft. (76.2 m) Total
Equivalent Length), refer to the Residential Piping and Longline Guide
line- Air Conditioners and Heat Pumps using Puron refrigerant.
3. For alternate liquid line options on 18-42 size units, see Product Data or
Residential Piping and Application Guideline
UNIT SIZE
(SERIES)
Deep Vacuum Method
The deep vacuum method requires a vacuum pump capable of
pulling a vacuum of 500 microns and a vacuum gage capable of
accurately measuring this vacuum depth. The deep vacuum method
is the most positive way of assuring a system is free of air and
liquid water. A tight dry system will hold a vacuum of 1000
microns after approximately 7 minutes. See Fig. 4.
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
Install Liquid−Line Filter Drier Indoor
!
CAUTION
1. Installation of filter drier in liquid line is required.
2. Filter drier must be wrapped in a heat−sinking material
such as a wet cloth while brazing.
Refer to Fig. 3 and install filter drier as follows:
1. Braze 5−in. liquid tube to the indoor coil.
2. Wrap filter drier with damp cloth.
3. Braze filter drier to above 5−in. (127 mm) liquid tube.
Flow arrow must point towards indoor coil.
4. Connect and braze liquid refrigerant tube to the filter drier.
VACUUM TIGHT
TOO WET
TIGHT
DRY SYSTEM
0
1
2
3
4
5
MINUTES
6
7
A95424
A95424
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage or improper operation.
LEAK IN
SYSTEM
MICRONS
Use refrigeration grade tubing. Service valves are closed from
factory and ready for brazing. After wrapping service valve with a
wet cloth, braze sweat connections using industry accepted
methods and materials. Consult local code requirements.
Refrigerant tubing and indoor coil are now ready for leak testing.
This check should include all field and factory joints.
Refrigerant tubes and indoor coil should be evacuated using the
recommended deep vacuum method of 500 microns. The alternate
triple evacuation method may be used (see triple evacuation
procedure in service manual). Always break a vacuum with dry
nitrogen.
Fig. 4 − Deep Vacuum Graph
Final Tubing Check
IMPORTANT: Check to be certain factory tubing on both indoor
and outdoor unit has not shifted during shipment. Ensure tubes are
not rubbing against each other or any sheet metal or wires. Pay
close attention to feeder tubes, making sure wire ties on feeder
tubes are secure and tight.
3
24ACB7
Connect vapor and liquid tubes to fittings on vapor and liquid
service valves (see Table 1.) Use refrigerant grade tubing
Table 2 – Accessory Usage
Required for Low Ambient
Cooling Applications
(Below 55°F / 12.8°C)
Yes
Yes (standard on some units)
Yes
Yes
(standard w/factory approved
indoor unit)
Accessory
Compressor Start Assist Capacitor and Relay
Crankcase Heater
Evaporator Freeze Thermostat
Hard Shutoff TXV
Liquid Line Solenoid Valve
No
Low-Ambient Pressure Switch
Support Feet
Winter Start Control
Yes
Recommended
Yes
Required for Long Line
Applications*
Yes
Yes (standard on some units)
No
Yes
(standard w/factory approved
indoor unit)
See Residential Piping
and Long Line Guideline
No
No
No
Required for Sea Coast
Applications
(within 2 miles/3.2 km)
No
No
No
Yes
(standard w/factory approved
indoor unit)
No
No
Recommended
No
* For tubing line sets between 80 and 200 ft. (24.38 and 60.96 m) and/or 35 ft. (10.7 m) vertical differential, refer to Residential Piping and Longline Guideline.
24ACB7
Make Electrical Connections
Be sure field wiring complies with local and national fire, safety,
and electrical codes, and voltage to system is within limits shown
on unit rating plate. Contact local power company for correction of
improper voltage. See unit rating plate for recommended circuit
protection device.
NOTE: Operation of unit on improper line voltage constitutes
abuse and could affect unit reliability. See unit rating plate. Do not
install unit in system where voltage may fluctuate above or below
permissible limits.
NOTE: Use copper wire only between disconnect switch and unit.
NOTE: Install branch circuit disconnect of adequate size per NEC
to handle unit starting current. Locate disconnect within sight from
and readily accessible from unit, per Section 440−14 of NEC.
Route Ground and Power Wires
Remove access panel to gain access to unit wiring. Extend wires
from disconnect through power wiring hole provided and into unit
control box.
WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or
death.
The unit cabinet must have an uninterrupted or unbroken
ground to minimize personal injury if an electrical fault should
occur. The ground may consist of electrical wire or metal
conduit when installed in accordance with existing electrical
codes.
Connect Ground and Power Wires
Connect ground wire to ground connection in control box for
safety. Connect power wiring to contactor as shown in Fig. 5.
DISCONNECT
PER N.E.C. AND/OR
LOCAL CODES
CONTACTOR
FIELD POWER
WIRING
3 PHASE ONLY
BLUE
FIELD GROUND
WIRING
GROUND
LUG
A94025
Fig. 5 − Line Connections
Connect Control Wiring
Route 24−v control wires through control wiring grommet and
connect leads to control wiring (See Fig. 7). Refer to Installation
Instructions packaged with thermostat.
Use No. 18 AWG color−coded, insulated (35_C minimum) wire. If
thermostat is located more than 100 ft. (30.48 m) from unit, as
measured along the control voltage wires, use No. 16 AWG
color−coded wire to avoid excessive voltage drop.
All wiring must be NEC Class 2 and must be separated from
incoming power leads.
Use furnace transformer, fan coil transformer, or accessory
transformer for control power, 24v/40va minimum.
NOTE: Use of available 24v accessories may exceed the
minimum 40va power requirement. Determine total transformer
loading and increase the transformer capacity or split the load with
an accessory transformer as required.
Final Wiring Check
IMPORTANT: Check factory wiring and field wire connections
to ensure terminations are secured properly. Check wire routing to
ensure wires are not in contact with tubing, sheet metal, etc.
Compressor Crankcase Heater
When equipped with a crankcase heater, furnish power to heater a
minimum of 24 hr before starting unit. To furnish power to heater
only, set thermostat to OFF and close electrical disconnect to
outdoor unit.
A crankcase heater is required if refrigerant tubing is longer than
80 ft. (24.38 m). Refer to the Application Guideline and Service
Manual Longline Section−Residential Split−System Air
Conditioners and Heat Pumps.
Airflow Selections (ECM Furnaces)
The ECM Furnaces provide blower operation to match the
capacities of the compressor during high and low stage cooling
operation. Tap selections on the furnace control board enable the
installing technician to select the proper airflows for each stage of
cooling. Below is a brief summary of the furnace airflow
configurations
1. The Y2 call for high stage cooling energizes the “Cool” tap
on the control board. The grey wire from cool tap is connected to tap 5 on the motor. Refer to the furnace Product Data
to find the corresponding airflow. If the airflow setting for
high cooling needs to be switched from tap 5 to a different
tap, jumper a connection from the cool tap to the desired tap
so that the Y2 signal is communicated via the cool tap to the
desired speed tap.
2. The Y1 call for low stage cooling energizes the “Fan” tap
on the control board. The red wire from the fan tap is connected to tap 1 on the motor. Refer to the furnace Product
Data to find the corresponding airflow. If the airflow setting
for low cooling needs to be switched from tap 1 to a different tap, jumper a connection from the Fan tap to the desired
tap so that the Y1 signal is communicated via the Fan tap to
the desired speed tap. The Y1 setting will also govern the
continuous fan airflow for the furnace.
Refer to the literature for the furnace for further details.
4
The variable speed furnaces provide blower operation to match the
capacities of the compressor during high and low stage cooling
operation. The furnace control board allows the installing
technician to select the proper airflows for each stage of cooling.
Below is a summary of required adjustments. See furnace
installation instructions for more details:
1. Turn SW1−−5 ON for 400 CFM/ton airflow or OFF for 350
CFM/ton airflow. Factory default is OFF.
2. The A/C DIP switch setting determines airflow during high
stage cooling operation. Select the A/C DIP switch setting
corresponding to the available airflow shown in the furnace
Installation Instructions that most closely matches the required airflow shown in the air conditioning Product Data
for HIGH speed.
3. The CF DIP switch setting determines airflow during low
stage cooling operation. Select the CF DIP switch setting
corresponding to the available airflow shown in the furnace
installation instructions that most closely matches the required airflow shown in the air conditioning Product Data
for LOW speed. If a higher or lower continuous fan speed is
desired, the continuous fan speed can be changed using the
fan switch on the thermostat. Refer to the furnace Installation Instructions for details of how to use this feature.
Airflow Selection for FV4C Fan Coils
The FV4 provides high− and low−stage blower operation to match
the capacities of the compressor at high− and low−stage.
To select recommended airflow, refer to the FV4C Installation
Instructions. The FV4C utilizes an Easy Select control board that
allows the installing technician to select proper airflows. This fan
coil has an adjustable blower−off delay factory set at 90 sec. for
high− and low−stage blower operation.
Install Electrical Accessories
Refer to the individual instructions packaged with kits or
accessories when installing.
Start−Up
!
CAUTION
UNIT OPERATION AND SAFETY HAZARD
Failure to follow this caution may result in personal injury,
equipment damage or improper operation.
S Do not overcharge system with refrigerant.
S Do not operate unit in a vacuum or at negative pressure.
S Compressor dome temperatures may be hot.
!
CAUTION
PERSONAL INJURY HAZARD
Failure to follow this caution may result in personal injury.
Wear safety glasses, protective clothing, and gloves when
handling refrigerant and observe the following:
SFront seating service valves are equipped with Schrader
valves.
SYSTEM FUNCTIONS AND SEQUENCE
OF OPERATION
The 24ACB7 models utilize a 2-stage cooling indoor thermostat.
With a call for first stage cooling, the outdoor fan and low-stage
compressor are energized. If low-stage cannot satisfy cooling
demand, high-stage is energized by the second stage of indoor
thermostat. After second stage is satisfied, the unit returns to
low-stage operation until first stage is satisfied or until second stage
is required again.
When both first stage and second stage cooling are satisfied, the
compressor will shut off. Therefore, with first stage of cooling Y1
is powered on; and with second stage of cooling Y1 and Y2 are
powered on. When a 2-stage unit is operating at low-stage, system
vapor (suction) pressure will be higher than a standard single-stage
system or high-stage operation.
Compressor Operation on 24ACB7 Models
The basic scroll design has been modified with the addition of an
internal unloading mechanism that opens a by-pass port in the first
compression pocket, effectively reducing the displacement of the
scroll.
The opening and closing of the by-pass port is controlled by an
internal electrically operated solenoid. The modulated scroll uses a
single step of unloading to go from full capacity to approximately
67% capacity. A single speed, high efficiency motor continues to
run while the scroll modulates between the two capacity steps.
Modulation is achieved by venting a portion of the gas in the first
suction pocket back to the low side of the compressor, thereby
reducing the effective displacement of the compressor. Full
capacity is achieved by blocking these vents, thus increasing the
displacement to 100%.
A DC solenoid in the compressor controlled by a rectified 24 volt
AC signal in the external solenoid plug moves the slider ring that
covers and uncovers these vents. The vent covers are arranged in
such a manner that the compressor operates at approximately 67%
capacity when the solenoid is not energized and 100% capacity
when the solenoid is energized. The loading and unloading of the
two step scroll is done “on the fly” without shutting off the motor
between steps.
NOTE: 67% compressor capacity translates to approximately
75% cooling capacity at the indoor coil.
Follow these steps to properly start up the system:
1. After system is evacuated, fully back seat (open) liquid and
vapor service valves.
2. Unit is shipped with valve stem(s) front seated (closed) and
caps installed. Replace stem caps after system is opened to
refrigerant flow (back seated). Replace caps finger-tight and
tighten with wrench an additional 1/12 turn.
3. Close electrical disconnects to energize system.
4. Set room thermostat at desired temperature. Ensure that set
point is below indoor ambient temperature and is set low
enough to energize desired stage. In order to start the system
in low stage, refer to the literature for the installed thermostat and adjust the set point so that the differential between
the room temperature and the set temperature energizes Y1.
5. Set room thermostat to COOL and fan control to ON or
AUTO mode, as desired.
6. Operate unit for 15 minutes. Verify system refrigerant
charge by measuring the sub-cooling for low stage and
comparing with the published sub-cool on the rating plate.
7. In order to switch the the system to high stage, refer to the
literature for the installed thermostat and adjust the set point
to a lower value so that the differential between the room
temperature and the set temperature energizes Y2. Verify
system refrigerant charge by measuring the sub-cooling for
high stage and comparing with the published sub-cool on
the rating plate.
5
24ACB7
Airflow Selection for Variable Speed Furnaces
24ACB7
Check Charge
NOTE: CHARGE IN HIGH STAGE ONLY
Factory charge amount and desired subcooling are shown on unit
rating plate. Charging method is shown on information plate inside
unit. To properly check or adjust charge, conditions must be
favorable for subcooling charging. Favorable conditions exist
when the outdoor temperature is between 70_F and 100_F
(21.11_C and 37.78_C), and the indoor temperature is between
70_F and 80_F (21.11_C and 26.67_C). Follow the procedure
below:
Unit is factory charged for 15ft (4.57 m) of lineset. Adjust charge
by adding or removing 0.6 oz/ft of 3/8 liquid line above or below
15ft (4.57 m) respectively.
For standard refrigerant line lengths (80 ft/24.38 m or less), allow
system to operate in cooling mode at least 15 minutes. If conditions
are favorable, check system charge by subcooling method. If any
adjustment is necessary, adjust charge slowly and allow system to
operate for 15 minutes to stabilize before declaring a properly
charged system.
If the indoor temperature is above 80_F (26.67_C), and the
outdoor temperature is in the favorable range, adjust system charge
by weight based on line length and allow the indoor temperature to
drop to 80_F (26.67_C) before attempting to check system charge
by subcooling method as described above.
If the indoor temperature is below 70_F (21.11_C), or the outdoor
temperature is not in the favorable range, adjust charge for line set
length above or below 15ft (4.57 m) only. Charge level should then
be appropriate for the system to achieve rated capacity. The charge
level could then be checked at another time when the both indoor
and outdoor temperatures are in a more favorable range.
NOTE: If line length is beyond 80 ft (24.38 m) or greater than 20
ft (6.10 m) vertical separation, See Long Line Guideline for
special charging requirements.
Final Checks
IMPORTANT: Before leaving job, be sure to do the following:
1. Ensure that all wiring is routed away from tubing and sheet
metal edges to prevent rub−through or wire pinching.
2. Ensure that all wiring and tubing is secure in unit before
adding panels and covers. Securely fasten all panels and
covers.
3. Tighten service valve stem caps to 1/12−turn past finger
tight.
4. Leave Owner’s Manual with owner. Explain system operation and periodic maintenance requirements outlined in
manual.
5. Fill out Dealer Installation Checklist and place in customer
file.
TROUBLESHOOTING
If the compressor fails to operate with a cooling call, the table
below (Resistance table) can be used to verify if there is any
damage to the compressor windings causing system malfunction.
Table 3 – Winding Resistance
Winding
Start
(S-C)
Run
(R-C)
Winding resistance at 70_F +/- 20_F
(21.11_C +/- 11.11_C)
24ACB724
24ACB736
24ACB748
24ACB760
1.64
1.52
1.86
1.63
1.30
0.88
0.52
0.39
Troubleshooting 24ACB7 units for proper switching
between low− and high−stages
Check the suction pressures at the service valves. Suction pressure
should be reduced by 3−10% when switching from low to high
stage.
NOTE: The liquid pressures are very similar between low− and
high− stage operation, so liquid pressure should not be used for
troubleshooting.
Compressor current should increase 20 to 45% when switching
from low to high stage. The compressor solenoid when energized
in high stage, should measure 24vac at the leads inside control box.
When the compressor is operating in low stage, the 24v DC
compressor solenoid coil is de−energized. When the compressor is
operating in high stage, the 24v DC solenoid coil is energized.
The solenoid plug harness that is connected to the compressor has
an internal rectifier that converts the 24v AC signal to 24v DC.
DO NOT INSTALL A PLUG WITHOUT AN INTERNAL
RECTIFIER.
Unloader Test Procedure:
The unloader is the compressor internal mechanism, controlled by
the DC solenoid, that modulates between high− and low−stage. If
it is suspected that the unloader is not working, the following
methods may be used to verify operation:
1. Operate the system and measure compressor amperage.
Cycle the unloader on and off at 30 second plus intervals at
the thermostat (from low− to high−stage and back to low−
stage). Wait 10 seconds after staging to high before taking a
reading. The compressor amperage should go up or down at
least 20 percent.
2. If step one does not give the expected results, remove the
solenoid plug from the compressor and, with the unit running and the Thermostat calling for high−stage, test the
voltage output at the plug with a DC voltmeter. The reading
should be 24 volts DC.
3. If the correct DC voltage is at the control circuit molded
plug, measure the compressor unloader coil resistance. The
resistance should be approximately 330 or 1640 ohms depending on unloader coil supplier. If the coil resistance is
infinite or is grounded, the compressor must be replaced.
MAJOR COMPONENTS
2−Stage Compressor
The 2−stage compressor contains motor windings that provide
2−pole (3500 RPM) operation.
Compressor Internal Relief
The compressor is protected by an internal pressure relief (IPR)
which relieves discharge gas into compressor shell when
differential between suction and discharge pressures exceeds and
550 − 625 psi. The compressor is also protected by an internal
overload attached to motor windings.
Compressor Control Contactor
The contactor has a 24 volt coil and is controlled by Y1 input from
the thermostat
High and Low Pressure Switches
High and low pressure switches are provided in line with the Y1
signal to the contactor for protection. The high pressure switch
mounted on the liquid tube is set to open at 670 psi and higher, and
the low pressure switch mounted on the suction tube opens at a
pressure of 50 psi and lower.
6
CARE AND MAINTENANCE
For continuing high performance and to minimize possible
equipment failure, periodic maintenance must be performed on this
equipment.
Variable Speed
Fan Coil
Thermidistat
Frequency of maintenance may vary depending upon geographic
areas, such as coastal applications. See Owner’s Manual for
information.
Two-Stage
Air Conditioner
THERMIDISTAT
TWO-STAGE
AIR CONDITIONER
O
O/W2/B
Heat Stage 1
W/W1
W1
Compressor Low
Y1
W2
Compressor High
Y/Y2
Y/Y2
Fan
G
G
24VAC Hot Heating
Rh
R
24VAC Hot Cooling
Rc
Dry Contact 1
D1
Dry Contact 2
D2
24VAC Common
C
Humidify
HUM
Outdoor Air Temp
OAT
DH
Remote Room Sensor
OAT/RRS Return
SRTN
Y1
Y1
REMOVE J2
JUMPER FOR
HEAT STAGING
Y2
REMOVE J1 FOR
DEHUMIDIFY
MODES
C
C
24ACB7
RVS/Heat Stage 2
Humidifier Solenoid
Valve
RRS
Outdoor Sensor
SRTN
Remote Room
Sensor
A09276
A09277
Edge Thermidistat Models TP-PRH-01 & TP-NRH-01
w/ Fan Coil & 2-Stage Air Conditioner
Thermidistat Model TSTATCCPRH01-B
w/ VS Furnace & 2-Stage Air Conditioner
Fig. 6 − Thermidistat Wiring with 2−Stage Puron refrigerant Air Conditioner
HUMIDFIER
(24VAC)
A09279
A09278
2-Stage Thermostat with Single-Stage Furnace and
2-Stage Air Conditioner
Single Stage Furnace with 2-Stage Air Conditioner
Fig. 7 − Generic Wiring Diagrams
(See Thermostat Installation Instruction for specific unit combinations)
7
LEGEND
24v Factory Wiring
24v Field Wiring
Field Splice Connection
24ACB7
A09306
PURONR (R−410A) REFRIGERANT QUICK REFERENCE GUIDE
S Puron refrigerant operates at 50−70 percent higher pressures than R−22. Be sure that servicing equipment and replacement
components are designed to operate with Puron refrigerant
S Puron refrigerant cylinders are rose colored.
S Recovery cylinder service pressure rating must be 400 psig, DOT 4BA400 or DOT BW400.
S Puron refrigerant systems should be charged with liquid refrigerant. Use a commercial type metering device in the manifold hose
when charging into suction line with compressor operating
S Manifold sets should be 700 psig high side and 180 psig low side with 550 psig low−side retard.
S Use hoses with 700 psig service pressure rating.
S Leak detectors should be designed to detect HFC refrigerant.
S Puron refrigerant, as with other HFCs, is only compatible with POE oils.
S Vacuum pumps will not remove moisture from oil.
S Do not use liquid−line filter driers with rated working pressures less than 600 psig.
S Do not leave Puron suction line filter driers in line longer than 72 hours.
S Do not install a suction−line filter drier in liquid line.
S POE oils absorb moisture rapidly. Do not expose oil to atmosphere.
S POE oils may cause damage to certain plastics and roofing materials.
S Wrap all filter driers and service valves with wet cloth when brazing.
S A factory approved liquid−line filter drier is required on every unit.
S Do NOT use an R−22 TXV.
S If indoor unit is equipped with an R−22 TXV or piston metering device, it must be changed to a hard shutoff Puron TXV.
S Never open system to atmosphere while it is under a vacuum.
S When system must be opened for service, recover refrigerant, evacuate then break vacuum with dry nitrogen and replace filter driers.
Evacuate to 500 microns prior to recharging.
S Do not vent Puron refrigerant into the atmosphere.
S Do not use capillary tube coils.
S Observe all warnings, cautions, and bold text.
S All indoor coils must be installed with a hard shutoff Puron TXV metering device.
Copyright 2015 Carrier Corp. S 7310 W. Morris St. S Indianapolis, IN 46231
Edition Date: 02/15
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
8
Catalog No: 24ACB7-5SI
Replaces: 24ACB7-4SI